Answer: The required value of Q+S-T is [tex]8m+7n-3.[/tex]
Step-by-step explanation: We are given the following values of Q, R, S and T :
[tex]Q=7m+3n,\\\\R=11-2m,\\\\S=n+5,\\\\T=-m-3n+8.[/tex]
We are to simplify Q + S - T.
To simplify the given expression, we must substitute the values of Q, S and T in the expression.
Therefore, we get
[tex]Q+S-T\\\\=(7m+3n)+(n+5)-(-m-3n+8)\\\\=7m+3n+n+5+m+3n-8\\\\=8m+7n-3.[/tex]
Thus, the required value of Q+S-T is [tex]8m+7n-3.[/tex]
